The long-term goal of this project is to develop a new approach for treatment of human pancreatic carcinoma. Currently there is no effective therapy for this disease and the mortality rate has not significantly improved for two decades. Over 90% of human pancreatic cancer manifests a codon 12 K-Ras mutation that is considered pathogenic, and selective inactivation of gain-of-function Ras signaling represents an attractive therapeutic approach. In the previous funding period we focused on Kinase Suppressor of Ras (KSR1) as a target for pancreatic cancer therapy. We showed that KSR1 mediates oncogenic Ras signaling without impacting the pleiotropic physiologic functions of Ras. KSR1 was obligate for Ras-mediated tumorigenesis induced by constitutively-activated epidermal growth factor receptor or K-Ras mutation. Further, a KSR1 phosphorothioate antisense oligonucleotide (AS-ODN) that inactivated KSR1 pharmacologically induced dose-dependent cure of K-Ras-dependent human pancreatic cancer xenografts in nude mice, without evidence of toxicity. Clinical trials using KSR1 AS-ODN in human pancreatic cancer are currently being planned. The focus of this proposal is to advance the scientific framework for these clinical trials, and to optimize treatment by monitoring drug uptake and specific biologic responses to drug in tumor cells during therapy. In Specific Aim 1 we will develop assays to assess correlation of KSR1 AS-ODN uptake to KSR1 activity in pancreatic cancer xenografts. We are currently developing an ultra-sensitive ELISA assay to measure plasma and tumor levels of KSR1 AS-ODN and its metabolites that is 10-fold more sensitive than presently available assays, and a real-time PCR assay to measure tumor cell KSR1 levels. These assays will enable establishment of correlations between drug delivery protocols, KSR1 target inactivation, and parameters of tumor cell response to KSR1 AS-ODN therapy. Specific Aim 2 will examine the efficacy of our KSR1 AS-ODN in new clinically-relevant pancreatic cancer models in transgenic mice. Specific Aim 3 explores an anti-angiogenic response to KSR1 inactivation, recently discovered by us. The potential added anti-angiogenic benefit might yield an unexpected dimension to our proposed pancreatic cancer therapy. The availability of KSR1 as a highly-specific tumor target that is not involved in regulating normal tissue Ras functions provides the proposed translational research project a unique opportunity to establish guidelines for clinical use of KSR1 AS-ODN therapy for human Ras-dependent tumors.